It is well established that recent medical advances have resulted in longer life expectancies. These changes in life expectancy when coupled with changes in population levels have yielded a population of elderly people that is much greater than ever before. For example, it is estimated that in 1902 about 2 million people in the United States were at least 65 years old. The latest census, however, reveals that approximately 24 million people in this country are at least 65. It is expected that this trend will continue.
Despite the ability to keep people alive longer, the human body still undergoes substantial changes as part of the aging process. The changes which are attributable to aging include changes to the capillaries in and near the skin, changes to the muscles and tissues below the skin, and changes to the resiliency of the skin. As a result of these changes in and near the surface of the skin, an elderly person who is confined to bed for an extended period of time is likely to develop the decubitus ulcers or pressure ulcers which are commonly known as bed sores. Bed sores are an ancient problem which recently have begun to reach catastrophic proportions due to the growing number of elderly people.
Bed sores are open ulcerations which generally appear in the skin which covers a bony prominence. Additionally, bed sores typically occur at weight bearing parts of the body. Since bed sores are most prominent among bed ridden or wheelchair ridden elderly patients the ulcers are most likely to appear on portions of the back which overlie prominent bones. For example in "Pressure Ulcers: Prevention and Treatment", Clinical Symposia, Vol. 31, no. 5, 1979, Agress and Spira estimate that 23% of bed sores occur adjacent the sacrum or lower spine, 24% are located at the base of the buttocks; 15% are located at the trochanter, which is located on the thigh bone in the vicinity of the hip; 8% are at the back of the heel; 7% at the ankle; 6% at the knees; 4% at the iliac crest, which is the front bony pretrusion of the hip; 3% at the elbows and 2% at the pretibial crest which is directly below the knee. Other significant areas of occurrence include the base of the skull, the chin and upper and lower portions of the back.
Bed sores often are analogized to icebergs in that only the tip of a large ulceration breaks through the skin. More specifically in most instances, the bed sore not only effects the upper layers of skin but also the underlying layers of fat and muscle and perhaps even the underlying bone. Bed sores are extremely difficult to treat, are very painful and have a major negative effect on the quality of life for bed ridden elderly people. As pointed out by Agress and Spira, in extreme instances, bacterial infection of the bed sore may be life threatening.
The name pressure ulcers implies that the principal source of bed sores is pressure. In fact the principal method for treating bed sores has been to eliminate or reduce pressure. For example many complicated and costly devices have been developed which effectively rotate patients periodically so that the weight bearing portions of the body are changed every few hours. Other devices and treatments have been developed to try to releave the pain and discomfort and to bring about healing of bed sores once they have occurred. These latter schemes have included the use of water beds, lambs' fleece and lambs' fleece treated with certain lubricating oitments and creams. None of these approaches have been very successful in either eliminating or treating bed sores.
It is now known that pressure is only one of several contributing factors which cause bed sores in elderly bed ridden patients. Other significant contributing factors include friction and heat. Friction is the resistance to sliding motion of two bodies pressed against one another. The general term friction encompasses static friction, which results from the resistance to motion in overcoming inertia, and dynamic friction, which is created by the irregularities of the two surfaces interlocked with one another. A significant force is required to overcome static friction and thus to obtain sliding movement of two bodies with respect to one another. Static friction ceases to be a significant factor after sliding momentum has been achieved between the two bodies. However dynamic friction manifests itself in the rubbing together of microscopic projections on the respective bodies. More particularly the dynamic friction caused by microscopic irregularities in all surfaces causes heat in proportion to the load and speed and effectively welds adjacent surfaces at their points of contact, resulting in tearing or galling.
When a soft material is pressed against a harder material and moved in sliding relation thereto, the softer material flows to conform to the topography of the hard material, thereby increasing the area of contact along with frictional forces and heat adjacent to the surface.
In general, a softer material wears faster than a harder material. Certain flexible materials such as the skin of a young person are quite elastic and will give when subjected to the forces of friction. However in older patients the skin is less elastic. Furthermore, if the skin of the older person is subjected to frequent frictional forces, it becomes even less elastic. If an elastic material, such as skin, has a hard backing, such as a bony protrusion under the skin, the natural elastic deformation of the skin is severely limited. The net result is that wear to skin will occur much more quickly in areas of skin which cover a boney prominence.
Wear of almost any surface subjected to friction is characterized by the removal of particles from the surface and by pitting. The loose removal particles causes further wear because of abrasion. Pitting of the surface further causes fatigue and weakening of the surface structure. Ultimately the wear attributable to friction eventually leads to fissures and cracks on the surface. Such faults if not treated immediately will grow because they are the weakest areas of the surface structure.
Accordingly, it is an object of the subject invention to provide a composite structure which substantially prevents bed sores.
It is another object of the subject invention to provide a composite pad structure with a very low coefficient of friction.
It is an additional object of the subject invention to provide a composite pad structure for preventing bed sores which can be placed between a patient and a supporting structure.
It is a further object of the subject invention to provide a composite pad structure for preventing bed sores which is comfortable to the patient and which cam be manufactured at a low cost.
It is yet another object of the subject invention to provide a composite pad structure which includes a low friction fabric and a lubricant.